Davy's attention was naturally arrested by such a statement, and, in pursuing the enquiry, he discovered a series of new facts:--he found that tellurium and hydrogen were capable of combining, and of forming a gas, to which he gave the name of _telluretted hydrogen_,--that, so far from tellurium preventing the decomposition of potash, it formed an alloy with potassium when negatively electrified upon the alkali--and, such was the intense affinity of potassium and tellurium for each other, that the decomposition of potash might be effected by acting on the oxide of the latter metal and the alkali, at the same time, by heated charcoal. With respect to the next subject of enquiry in these papers, _viz._ whether sulphur, phosphorus, and carbon, in their ordinary forms, may not contain hydrogen, it would appear that from an experiment performed by Mr. Clayfield, and which Davy witnessed at Bristol in the year 1799, he was very early led to suspect the existence of hydrogen in sulphur; but it was not until 1807, that he entered upon the investigation of the subject. From the general tenor of his experiments he concluded that, in its common state, it may be regarded as a compound, of small quantities of oxygen and hydrogen, with a large quantity of a basis which, on account of its strong attractions for other bodies, has not hitherto been obtained in its pure form. The same analogies apply to phosphorus and carbon. His conclusion was mainly derived from the fact, that hydrogen is produced from sulphur and phosphorus in such quantities by Voltaic electricity, that he thinks it cannot well be considered as an accidental ingredient in them: the presence of oxygen, he contends, may be inferred from the circumstance that, when potassium is made to act upon these bodies, the sulphurets and phosphurets so formed evolve by the action of an acid less hydrogen, in the form of compound inflammable gas, than the same quantity of potassium in an uncombined state. The question, however, still remains in considerable doubt; and in his "Elements of Chemical Philosophy," published four years afterwards, he admits that no accurate conclusions have been formed on the subject. In his second Bakerian Lecture of 1807, Davy had given an account of an experiment in which boracic acid appeared to be decomposed by Voltaic electricity, a dark-coloured inflammable substance separating from it on the negative surface. In the memoir now under consideration, he procured the basis by heating together boracic acid and potassium, when he ascertained it to be a peculiar inflammable matter, which, after various experiments upon its nature, he was inclined to regard as metallic; on which account he proposed for it the name of _Boracium_. At about the same period, MM. Gay Lussac and Thénard were engaged in investigating the same subject in France, and they anticipated him in some of the results.